1. Field of the Invention
The present invention relates to a method of manufacturing printed circuit boards. More particularly the present invention relates to a method of manufacturing printed circuit boards formed with a flux preventive film on a component side surface.
2. Description of the Prior Art
Where components are mounted on a prior art printed circuit board, the mounting is performed by soldering component leads to a junction land of the printed circuit board through through-holes thereof.
In order to prevent a flux from rising from the component soldering surface to the component surface during the above-mentioned mounting, a technique has been performed by which the entire surface of the component surface is coated with a flux preventive film. This flux preventive film is by coating a solder resist ink containing silicon and/or fluoroplastics of a prior art solder resist ink by means of silk screen printing. Thus flux preventative film has a surface tension with a contact angle of 100 degrees or more.